The present invention relates to a method and apparatus for processing meat products and more particularly to a method and apparatus where the meat products are heated or cooled by passage through a shell-and-tube heat exchanger. The invention particularly contemplates the heating or cooling of such meat products in forming various edible products.
In the prior art, the processing of such meat products or the like has presented various problems. In particular, where passage of the meat products is contemplated through equipment presenting small or tortuous passages, it has been found generally necessary to first reduce the meat product to essentially a flowable or pumpable consistency in order to prevent blockage from occurring during passage of the meat product into and through the equipment components. In the context of this invention, "pumpable" is intended to mean a capability of being transferred or moved, freely or without further assistance through processing equipment by a positive displacement type pump. However, in the formation of edible components, it is important to minimize mechanical working in order to maintain the original flavor and texture of the products. It was generally found to be difficult or impossible to achieve the goal of minimum mechanical working with the product being reduced to a substantially flowable or pumpable consistency.
Also in many prior art processes, usually because of equipment design such as surge tanks or the like preventing processing on a first-in, first-out basis, different portions of the meat products were commonly heated for different amounts of time. This also resulted in undesirable variation in flavor and texture of the finished product as well as susceptibility to bacterial growth.
Processing of various meat products, including beef, poultry, pork, etc., has often required initial separation of their lean meat portions from accompanying liquefiable components including fats and oils. Trimmings obtained from animal carcasses during butchering operations in packing houses and the like are of particular concern within the present invention because of the substantial amounts of lean meat material, both in the form of muscle and connective tissue, which is contained within the fat trimmings. Generally, such trimmings consist of large amounts of fats combined with relatively small lean meat portions in the form of muscle meat and/or connective tissue. Certain materials, particularly inedible products, may even contain bone particles which will normally remain with the lean meat component.
Furthermore, meat products of the type contemplated by the present invention may include substantial non-meat components such as vegetable or grain extenders and mixed components for certain applications. For example, the invention may be employed in the preparation of pizza toppings and other mixtures including meat products, vegetable products and/or other components as well.
The lean meat portion must often be removed from the fat portion, or the fat portion at least be reduced in percentage, in order to produce acceptable food products such as sausages, frankfurters, or chunked-and-formed jerky. In addition to beef products, it will be apparent that the invention also contemplates other meats presenting further problems as further defined therein.
At the same time, it will also be apparent that the present invention is not limited to a method and apparatus for separating lean meat and the like from liquefiable portions. For example, substantial portions of the animal carcass could be treated or processed according to the method and apparatus of the present invention in order to obtain final products including a selected percentage of lean meat. Thus, although the invention preferably contemplates processing of fat trimmings including substantial amounts of fat or the like and as little as 2 to 20% lean meat, the invention may also be employed in the processing of meat trimmings or products including substantially greater amounts of lean meat and possibly bone particles or ash.
The difficulty in processing meat products of the type referred to above arises generally from the need in certain applications for first removing at least a portion of the liquefiable fat in order to achieve a satisfactory proportion of lean meat and fat for use in various food products. In the past, meat products, such as beef trimmings including unacceptably high percentages of fat, have conventionally been separated in rendering processes where the fat and lean meat portions are heated to a suitable temperature in order to render or liquefy the fats and oils in order to facilitate their separation from the lean meat portion. The lean meat portion has commonly been separated from the rendered fats and oils for example in centrifuges. However, problems have arisen because of the need for first heating the meat products to a suitable temperature in order to render the fats and oils. Since the lean meat portion is heated at the same time, it becomes particularly susceptible to bacterial growth which undesirably affects its quality for use in various food products.
The prior art processes and problems summarized above are particularly contemplated by the present invention in connection with the handling of relatively large chunks or pieces of meat products which must be rapidly and efficiently processed in order to produce a resulting meat product of the highest possible quality. The large pieces of meat may have a major dimension of up to 15 or 20 inches, for example, typically in the form of fat trimmings from slaughterhouse operations.
In some applications, it may be desirable to further process the fat trimmings, for example, by heating, in order to remove a substantial portion of the fat and recover the remaining lean meat portion. On the other hand, such fat trimmings may be combined with other components and then cooled to form a meat product such as sausage having a relatively high fat content. In either type of application, it is desirable to achieve the respective end product with relatively minimum mechanical working which normally tends to undesirably impair the texture or quality of the product.
At the same time, typical processing equipment, of a type including tube type heat exchangers, requires movement of the meat products into and through passages which are generally restricted or tortuous. The large pieces of meat products referred to above cannot be introduced in that form into such equipment since they cannot be readily caused to continuously enter the restricted passages.
The lean meat portions comprise fiber having a tendency to amass or pile up at the entrance to the restrictive passages. Even if the individual fibers or fiber chains are of a size suitable for entering the restricted passages, groups of the fibers or fiber chains often interact to form a larger mass which cannot readily be pumped or moved into the passages. Also, individual fibers or chains may be compressed in an "accordion effect" which substantially increases their effective size and further adds to the problem of blockage.
Because of this problem, most prior art processes dealing with meat products of the type contemplated by the present invention first reduce the meat products to a generally flowable or pumpable condition so that it can be caused to enter such restrictive passages by means of a pump or the like without further assistance. However, blockage commonly occurs in such processing equipment even with the product being in such a flowable condition.
Prior art processes such as those set forth above have been found to be relatively inefficient either in terms of the design of the equipment or in the method in which the meat products are processed and the resulting quality of the meat products. Accordingly. there has been found to remain a need for a method and apparatus for efficiently and effectively heating or cooling meat products and the like and more particularly for processing meat trimmings and the like in order to separate and recover lean meat portions.